This invention relates to compositions and methods of using the compositions in preparing ferrous metal components for subsequent surface electroplating by preparing a solution containing an acid and sequestering agents, immersing the components and abrading media in the solution, and agitating the components and the abrading media while maintaining the components and the media immersed in the solution. Similar technology has been known heretofore from such disclosures as Hays U.S. Pat. No. 2,890,944; a series of United States Patents to Herman Ben Snyder including U.S. Pat. Nos. 2,940,838; 2,981,610; 3,052,582; and 3,061,494; and Michaud et al U.S. Pat. No. 4,491,500.
In accordance with the improvements of the present invention, the compositions are in dry granular form. In dry granular form, the composition has, by weight percent, up to about 40% of oxalic acid crystals; up to about 30% of a crystalline phosphorus sequestering agent; the ratio by weight of oxalic acid crystals to sequestering agent crystals being in a range of from about 2:1 to about 0.4:1; a quantity of a liquid amine ammonifying agent sufficient and effective for adjusting the pH of the solution formed on dissolving the composition in water to about 3.5; a quantity of a non-foaming non-ionic surfactant sufficient and effective for accomplishing wetting of the composition; and a quantity of a granular absorbent sufficient to make up the remainder of the composition and effective to absorb said liquid amine ammonifying agent and serve as a carrier therefor.
It has been known heretofore in the manufacture of ferrous metal components that electroplating of such components may serve the dual functions of protecting the ferrous material against rust or other deterioration and enhancing appearance. For such reasons, it is commonly done to plate hand tools such as wrenches and the like with bright electroplate finishes. In preparing components for such finishing, it is important that the surfaces to be plated have a certain degree of smoothness for appearance sake, and sometimes important that they be polished. While such polishing has been done in a number of different ways, chemical processes for metal removal have achieved some success and acceptance, and have followed generally the teachings of the prior patents listed above.
In processes of the type described, there is a constant balancing of harshness against productivity. In attempts to achieve high productivity of components and short cycle times for the use of equipment, some users have attempted the use of strongly acidic solutions. In attempts to achieve desirable surface finishes, other users have attempted the use of less acidic solutions. In both instances, problems may be encountered with exhaustion of solutions used and effluents created. Attempts at prolonging the usefulness of solutions have involved the use of sequestering agents to avoid exhaustion of working solutions.